6 - Ecological factors in population persistence

M628 bio 3115 universit dottawa university of ottawa

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Unformatted text preview: immigration rates are not high enough, sink populations will go extinct. E.g. Acorn woodpecker populations in New Mexico are found in small populations in isolated oak canyons. The graph shows a result of a simulation model to predict the effect of environmental unpredictability and immigration rates on viability of woodpecker populations. Median persistence (yr) Metapopulation structure: conservation implications Melanerpes formicivorus 500 400 300 200 100 0 0 1 2 3 4 5 Immigration rate (indiv/yr) M6.29 BIO 3115 Université d’Ottawa / University of Ottawa Melanerpes formicivorus Simulated, totally isolated small populations became extinct within 20 yrs. However, actual small populations survived for over 70 yrs Hence, in these sink populations, migration must be important! From the simulation it appears that the immigration rate must be about 3 individuals/yr. Median persistence (yr) Metapopulation structure: conservation implications 500 400 300 200 100 0 0 1 2 3 4 5 Immigration rate (indiv/yr) M6.30 BIO 3115 Université d’Ottawa / University of Ottawa M6.15 BIO 3115 Conservation Biology % original variation remaining The role of immigration in maintaining genetic variability (an example from grizzly bears) immigration of 2 unrelated bears every 10 years substantially reduces loss of variability 100 95 90 85 N=100, isolated Exchange 80 75 0 20 40 60 80 100 120 Years M6.31 BIO 3115 Université d’Ottawa / University of Ottawa Influence of habitat distribution on extinction risk/persistence The geometry, size and spatial distribution of suitable habitat in the landscape can have a significant effect on extinction risk. e.g. The cougar occurs in Santa Anna mountains in small mountain ranges linked by riparian corridors (these are crucial for movement of cougars between semi-isolated populations). Destruction of corridors caused by development would prevent migration between populations. The development plan was modified to protect the corridors. Felis concolor M6.32 BIO 3115 Université d’Ottawa / Uni...
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This document was uploaded on 03/11/2014 for the course BIO 3115 at University of Ottawa.

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